273
controls leading to the enhancement of their catalytic activity. According to several
studies, cyclodextrins could be also used as reducing agents of metal precursor by
their sugar-like reducing properties.
Due to a dynamic organization at the surface of metal nanoparticles, the classical
mass transfer property of cyclodextrins has also been exploited with solventdispersed nanoparticles or nanoparticles immobilized on a support. The catalytic
activity is generally improved thanks to the inclusion complex formed between the
substrate and the cyclodextrin via hydrophobic interactions. This inclusion complex
could also, in some cases, improve the selectivity of the reaction by inhibiting some
side reactions. Cyclodextrins could also serve as agent to get confining catalytic
systems by forming supramolecular hydrogels where the metal nanoparticles can be
embedded. This confinement could improve the selectivity of the reaction, the catalytic activity by enhancing the proximity between the substrate and the metal particles, and also the stability leading to longer lifetime which is very important from
an economical point of view.
The combination of cyclodextrin and polymer in a physical mixture and as
cyclodextrin- based polymer where the cyclodextrin is directly incorporated into the
polymer structure has recently proven to be very promising both in the use of
nanoparticles dispersed into a solvent or immobilized on cyclodextrin polymer
where it could play the role of stabilizing agent and also the role of support.
In the near future, the perspectives and the challenges are numerous concerning
the development of nanoheterogeneous catalysis in the presence of cyclodextrin.
Indeed, in terms of nanocatalyst design, in order to draw a parallel with the supramolecular chemistry defined by Jean-Marie Lehn, it would be very interesting, in
the case of cyclodextrin-based nanoheterogeneous catalytic systems, to develop
more complex and more controlled structures in order to work at a higherdimensional scale. The preparation of supramolecular materials could lead to some
synergistic effects with the aims to improve the catalytic activity or selectivity, for
example. The design of cyclodextrin-based metal-organic frameworks containing
metal nanoparticles could answer to some of these issues. From a catalytic point of
view, always keeping in mind the multi-task agent properties of cyclodextrin for the
development of nanoheterogeneous catalysis, it would be innovative to consider
multimetallic nanocatalysts applied for cascade reactions for the valorization of biosourced compounds.
References
Alvarez J, Liu J, Román E, Kaifer AE (2000) Water-soluble platinum and palladium nanoparticles
modified with thiolated β-cyclodextrin. Chem Commun:1151–1152. https://doi.org/10.1039/
b002423f
Astruc D, Liang LY, Rapakousiou A, Ruiz J (2012) Click dendrimers and triazole-related aspects:
catalysts, mechanism, synthesis, and functions. A bridge between dendritic architectures and
nanomaterials. Acc Chem Res 45:630–640. https://doi.org/10.1021/ar200235m
5 Metal Nanoparticles and Cyclodextrins for Catalytic Applications
controls leading to the enhancement of their catalytic activity. According to several
studies, cyclodextrins could be also used as reducing agents of metal precursor by
their sugar-like reducing properties.
Due to a dynamic organization at the surface of metal nanoparticles, the classical
mass transfer property of cyclodextrins has also been exploited with solventdispersed nanoparticles or nanoparticles immobilized on a support. The catalytic
activity is generally improved thanks to the inclusion complex formed between the
substrate and the cyclodextrin via hydrophobic interactions. This inclusion complex
could also, in some cases, improve the selectivity of the reaction by inhibiting some
side reactions. Cyclodextrins could also serve as agent to get confining catalytic
systems by forming supramolecular hydrogels where the metal nanoparticles can be
embedded. This confinement could improve the selectivity of the reaction, the catalytic activity by enhancing the proximity between the substrate and the metal particles, and also the stability leading to longer lifetime which is very important from
an economical point of view.
The combination of cyclodextrin and polymer in a physical mixture and as
cyclodextrin- based polymer where the cyclodextrin is directly incorporated into the
polymer structure has recently proven to be very promising both in the use of
nanoparticles dispersed into a solvent or immobilized on cyclodextrin polymer
where it could play the role of stabilizing agent and also the role of support.
In the near future, the perspectives and the challenges are numerous concerning
the development of nanoheterogeneous catalysis in the presence of cyclodextrin.
Indeed, in terms of nanocatalyst design, in order to draw a parallel with the supramolecular chemistry defined by Jean-Marie Lehn, it would be very interesting, in
the case of cyclodextrin-based nanoheterogeneous catalytic systems, to develop
more complex and more controlled structures in order to work at a higherdimensional scale. The preparation of supramolecular materials could lead to some
synergistic effects with the aims to improve the catalytic activity or selectivity, for
example. The design of cyclodextrin-based metal-organic frameworks containing
metal nanoparticles could answer to some of these issues. From a catalytic point of
view, always keeping in mind the multi-task agent properties of cyclodextrin for the
development of nanoheterogeneous catalysis, it would be innovative to consider
multimetallic nanocatalysts applied for cascade reactions for the valorization of biosourced compounds.
References
Alvarez J, Liu J, Román E, Kaifer AE (2000) Water-soluble platinum and palladium nanoparticles
modified with thiolated β-cyclodextrin. Chem Commun:1151–1152. https://doi.org/10.1039/
b002423f
Astruc D, Liang LY, Rapakousiou A, Ruiz J (2012) Click dendrimers and triazole-related aspects:
catalysts, mechanism, synthesis, and functions. A bridge between dendritic architectures and
nanomaterials. Acc Chem Res 45:630–640. https://doi.org/10.1021/ar200235m
5 Metal Nanoparticles and Cyclodextrins for Catalytic Applications